SSH – How to Close (Kill) SSH ControlMaster Connections Manually

connection-sharingssh

With the following .ssh/config configuration:

ControlMaster auto
ControlPath /tmp/ssh_mux_%h_%p_%r
ControlPersist 4h

How to close the persisting connection before the 4 hours?

I know you can make new connections, but how to close them (all)?

Maybe there is a way to show all the persisted connections and handle them individually but I can not find it.

Best Answer

From the manual:

-O ctl_cmd
Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: check (check that the master process is running), forward (request forwardings without command execution), cancel (cancel forwardings), exit (request the master to exit), and stop (request the master to stop accepting further multiplexing requests).

Older versions only have check and exit, but that's enough for your purpose.

ssh -O check host.example.com

If you want to delete all connections (not just the connection to a particular host) in one fell swoop, then fuser /tmp/ssh_mux_* or lsof /tmp/ssh_mux_* will list the ssh clients that are controlling each socket. Use fuser -HUP -k tmp/ssh_mux_* to kill them all cleanly (using SIGHUP as the signal is best as it lets the clients properly remove their socket).

Related Solutions

Ssh – Multiple ‘Host *’ in ssh_config

From the ssh_config manual:

Since the first obtained value for each parameter is used, more host-specific declarations should be given near the beginning of the file, and general defaults at the end.

So in your example, all hosts will use User harleypig and IdentityFile ~/.ssh/personal_id_rsa.

Think of Host directives with wildcards as fallbacks: use the following settings only if they haven't been set yet. You need to write something like this:

Host host1
Hostname host1.com
Host host2
Hostname host2.com
Host host*
User harleypig
IdentityFile ~/.ssh/personal_id_rsa

You can put multiple patterns on a Host line if a given set of host aliases can't be matched with wildcards, e.g. Host host* more* outlier.

Linux – Exit All SSH Connections and Close PuTTY with One Command

Try using the ssh connection termination escape sequence.

In the ssh session, enter ~. (tilde dot). You won't see the characters when you type them, but the session will terminate immediately.

$ ~.
$ Connection to me.myhost.com closed.

From man 1 ssh

The supported escapes (assuming the default ‘~’) are:
 ~.      Disconnect.
 ~^Z     Background ssh.
 ~#      List forwarded connections.
 ~&      Background ssh at logout when waiting for forwarded 
         connection / X11 sessions to terminate.
 ~?      Display a list of escape characters.
 ~B      Send a BREAK to the remote system (only useful for SSH protocol
         version 2 and if the peer supports it).
 ~C      Open command line.  Currently this allows the addition of port 
         forwardings using the -L, -R and -D options (see above). It also
         allows the cancellation of existing remote port-forwardings using 
         -KR[bind_address:]port.  !command allows the user to execute a 
         local command if the PermitLocalCommand option is enabled in
         ssh_config(5).  Basic help is available, using the -h option.
 ~R      Request rekeying of the connection (only useful for SSH protocol 
         version 2 and if the peer supports it).

Best Answer

Related Solutions

Ssh – Multiple ‘Host *’ in ssh_config

Linux – Exit All SSH Connections and Close PuTTY with One Command

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